Incandescent lamp.



PATENTED SEPT. 4, 1906.

J. w. FoRsTBR. INGANDBSGENT LAMP.

APPLICATION IILEDIAR. 24. 1905.

- the invention.

UNITED STATES EnTENT oEEIoE. i

Specication of Letters Patent.

Patented sept. 4, ieee.

Application filed March 24, 1905. Serial No. 251,725.

To all who'mI it may concern.-

Be it known that I, JAMES WRIGHT Fons-` `TER, a citizen of the UnitedStates, residing at Chicago, in the county of Cook and State ofIllinois, have invented new and useful Improvements in IncandescentLamps, of which the following is a specification.

This invention relates to incandescent lam s. c j

T e object of the invention is to increase the power and efficiency ofincandescent lamps operated by electricity and to reduce the expense ofthis method of illumination.

In incandescent electric lamps at present used a filament of carbon isarranged in a vacuum, and whena current of electricity is passed throughthe filament the heat resulting from the resistance of the carbon raisessaid carbon to a state of incandescence. The heat thus generatedradiates from the filament and is dissipated and Wasted.

It is one object of the present invention to provide a heat-absorbingsurface closely adjacent to the incandescent filament to receive andabsorb heat therefrom, said surface becoming heated thereby toa sta teof independent incandescence. A

In one form of the invention avacuum-bulb is provided, into which'anaxial pole projects, bearing the material which is to be renderedincandescent by heat received from the filament, and a filament of highresistance to serve as a conductor for the electric current is coiledaround the pole closely adjacent to said heat-absorbing surface. Heatfrom the filament is radiated to said surface and raises the temperaturethereof, and some heat is radiated back from said surface to thefilament, thus serving to conserve the heat of the filament.

In order to support the polar incandescent surface suitably, theinvention also comprises means to allow for expansion and contraction ofthe pole and the contents thereof by providing a chamber within the poleand a passage vtherefrom to the external air.

Other objects of the invention appear here7 inafter. l

In the accompanying drawings, Figure .1 represents one of my improvedlamps, partly in longitudinal section. Fig. 2 represents, partly insection, a detail of another form of l Figs. 3, 4, and 5 represent,partly in section, details of still other forms.

Referring to the drawings, 1 is a glass bulb Similar to those ordinarilyused for incandescent electric lamps containing a vacuum. Within thebulb is a filament 3, having high electrical resistance, connected toterminals of an Aoutside electrical current through leading-1n wires 4;It isshown in the drawings as it may be arranged in connection with anEdison base 5 of the type now in use, in which one electrical terminal6- is at the axis and the other terminal 7 is at the screw cir-`cumference of the base. The interior of the bulb also contains withinthe vacuum and adjacent to the filament 3 a suitable substance 10, whichis arranged to absorb heat from the filament and Whichbecomesluminiferous from the heat thus absorbed. This is hereinafter referredto as the luminiferous material. While the use of a refractorynon-conductor of electricity for this material is preferredsuch asmagnesia, alumina, or thoria-it is not necessary that the material benon-combustible, because it is surrounded by the vacuum. Theluminiferous material need not under all circumstances be anon-conductor of electricity. The advantage of employing a nonconductivematerial is that if such material be used 'less pains need be taken tokeep the yfilament out of contact therewith, While if a conductivematerial be employed it is desirable to mount the filament so that itwill be closely adjacent but not in contact with such material.

The luminiferous material may be mounted Within the vacuum and adjacentto the filament in any suitable Way. A convenient Way is illustrated inthe drawings and consists of a central pole or support 2, which projectsinto the bulb from the base thereof. The luminiferous material may besupported by this pole and the filament 3 coiled spirally around thesame adjacent thereto, and the filament may be anchored to the pole atone or more places,.as indicated at 9. In Figs. 12 and 3 theluminiferous material 10 is mounted directly on the glass of the pole.In Fig. 1 it is separated from direct contact with the pole by anintermediate casing or sack 11, of asbestos or other non-conductor ofheat, and in Fig. 4 it is separated by the vacuum, being carried on aseries of small piers 12. In Fig. 1 the material is mounted on theoutside of the asbestos sack, and the latter is mounted on the pole. Ifa casing be employed, as is indicated in Fig. 1, the same may be eitherpermanently or removably afiixed to the pole and may consist of a tubeor sack, of a suitable non-conducting fabric or substance,

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pole from the intense heat. -is preferably arranged close to the surfaceof which may. incase'the pole and at the same time bear' theluminiferousmaterial on its outer surface, thus protecting the glass of the Thefilament 3 .the filament radiates heat to the adjacent layer ofluminiferous material 10, which in turn becomes incandescent because ofthe heat thus received. This is additional to the incandescence of thefilament and the operation of producing. it does not detract from theincandescence of the .filament itself. On the contrary, it conservesheat, and heat is radiated from it back again to the filament.

The interior of the pole 2 may be hollow, and. `openings 8 aiiord freecommunication between said interior and the outside air. The

expansion and contraction of the pole, due to the changes of temperatureat its surface, are

- are visible from all sidesof the lam 4 Iii 3 a form is shown havinghigher thus prevented from injuring the remainder of the lam When thepole expands, air may' enter t ough these openings, and when the airWithin expands from the heat of the pole it may pass out Withoutincreasing the pressure within.

In the form of .the invention in Fig. 1, in which asbestos or otheropaque material in cases the pole, the light from one side of the poleis obscured from the observer, only the side near him be' visible.- Inthe form shown in Fig. 2 the uminifrous material is mounted directly onthe glass pole and is in the form of a spiral strip. The glass beingtransparent, it follows that when the strip becomes luminous practicallyall parts of it efficiency for conservation of heat. In this form theole has a spiral groove in its exterior su ace, which groove is coatedwith .the secondarily luminous strip, with. a V- shaped enterior, thefilament lying close thereto Awithin the V, either in contact or 1nearly in contact, as may be' desired. In

thiswformthe filament being half surrounded by the-secondarily luminousmaterial, half of. the heat-rays which radiate kfrom it strike `said"substance, and for the same reason a lar er roportion are radiatedbackin turn to t e lament. A v

` Inasmuch as the luminous strip is always in ava'cuum it maybe made ofany material which can be rendered incandescent by heati .Preferably itis madeof a materialwhich becomes incandescent at alow temperature, and.it may be mounted idirectly upon-the glass, or there may. be anintervening refractory substance or non-conductor of heat toV protectthe pole from the effects of its heat.

In the form indicated in Fig. 4. the pole is protected by carrying thefilament 'and secondarily luminous material ii on a series of smallsuplports, bothy being entirely surrounded by-.t e. vacuum, and. thevacuum thus protects the central pole. It is obvious also that bysuitably mo ifying the construction the central pole might be dispensedwith al.

use are supported. One such modificationI is shown` in Fig. 5, in whicha V-shaped strip of material is arranged 'in spiral form, the filamentlying within the V. This material is strongenough to sustain its -ownWeight, and, as in the other forms, the strip may be ar'- ran ed withthe side toward the filament a rea y absorbent of heat and the sideremote from the filament rovided with a non-conducting or non-ra 'atingsurface to retard the emission of heat from the strip except in thedirection ofthe filament.

The. luminiferous substance may be made in any suitable way and may beeither in the form of a continuous strip or may be a fabric renderedrefractory by thoria or otherwise, while if saine be kept out of contactwith the filament the side nearest the filament may be coated Withlampblack or other ready absorbent of heat, While the other side may beleft with a White surface, which radiates heat less rapidly. j

1. In an incandescent lamp, a bulb with a vacuum and filament therein,and connecl tions for an electrical current, in combination with aheat-absorbingl substancev arranged close to the filament, and means toretard the emission of heat-from the side of said heat-absorbingsubstance v.which `is remote fromthe filament.

2. In an incandescent lamp, a bulb with a` vacuumv and 'filamenttherein, andconnections for an electrical current, in combination with aheat-absorbing substance arranged close to the lament,` means to retardthe emission of heat 'fromthe side of said heatabsorbing substance whichis remote from the filament, and a support forsaid-substance Within thebulb. l i. j

3. In an incandescent lam a bulb with a vacuum and filament therein, andconnections for an electricalcurrent, incombination `with aheat-absorbing substance arranged 4close to the filament, means toretard the emission of heat from the side of said heat- -absorbingsubstance which is remote from the filament, and a trans arent supportfor said substance within-the ulb.

4. In. an incandescent lamp, a bulb with a vacuum and filament therein,and connections for'an electrical current, in combination with aheat-absorbi I.substance arranged within the vacuum an close to thefilament,

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a suport for said substance Within the bulb, there eing a non-conductorof heat between said substance and its su port.

5. In an incandescent Iamp, a bulb with a vacuum and filament therein,and connections for an electrical current, in combination with aheat-absorbing substance arranged close to the filament, means to`retard the emission of heat from said substance on the side remote fromsaid filament, and a support projecting within the bulb and attached tosaid substance at intervals.

6. In an incandescent lamp, a bulb with a vacuum and filament therein,and connections for an electrical current, in combination with aheat-absorbing substanceV arranged in the form of a strip close to thefilament, and means to retard the emission of heat from the side of saidstrip which is remote from the filament.

7. In an incandescent lamp, a bulb with a' vacuum and filament therein,and connections for an electrical current, in combination with aheat-absorbing substance arranged in theform of a strip close to thefilament and, t6"s`ome extent, surrounding the same and approximatelyparallel therewith, and means to retard the emission of heat from theside of said strip which is remote from the filament.

8. In an incandescent lamp, a bulb with a vacuum and filament therein,and connections for an electrical current, in combination with a supportprojectin centrallyqwithin the bulb, and a heat-absor ing substancearranged with the filament in spiral, form around said support andsupported thereby, and means to retard the emission of heat from 'theside of said heat-absorbing substance which is` remote from thefilament.

9. In an incandescent lamp, a bulb with a vacuum and filament therein,and connections for an electrical current, in combination with a supportprojecting within the bulb i Vand a heat-absorbing substance arrangedwith the filament around the support, and means to retard the emissionof heat from the side of said' heat-absorbing substance which is remotefrom the filament, said interior support being hollow, with a passagewaycommunicating between the interior thereof and the outside air.

In testimony whereof I affix my signature in presence of the subscribingwitnesses.

WILLIAM H. WALTKING, J. ELIZABETH TIcHLoFEN- y

